Col de Mantet

Overview

Col de Mantet is an HC climb in France that runs 10.4 km from a start elevation of 769 m to a summit at 1,774 m. Over that distance it delivers a net elevation gain of 1,005 m at an average gradient of 9.69%. That average alone places it among the hardest paved climbs a rider will face: sustaining nearly double-digit percentages for over ten kilometres is a serious, sustained effort with no easy way to hide from the grade.

The net gain of 1,005 m does not tell the whole story. Total ascent on the climb is 1,400 m, which means roughly 395 m of the vertical you climb is later given back and re-earned across dips and rolls. That undulation matters: every metre of descent is a metre you have to climb twice. Expect the effort to feel harder than the net numbers suggest, and plan for the punchy re-accelerations that come after each brief drop.

How the Gradient Unfolds

The 9.69% average smooths over a profile that is anything but steady. Some sections ease off and give brief recovery, while others rear up well beyond the average and force you out of the saddle. With 395 m of extra ascent baked into the total, the climb repeatedly gives back height and demands you regain it.

• Short flatter or false-flat stretches where you can recover cadence
• Repeated dips followed by punchy re-climbs that reset your rhythm
• Sustained double-digit ramps that sit well above the 9.69% average
• A steepest pitch that spikes hard and rewards being in your easiest gear early

Pacing Notes

On a climb this irregular, chase even effort, not even speed. Your pace will swing wildly between the recovery stretches and the steep ramps, and that is fine. Anchor your effort to your sustainable power output and hold a target you can carry across the full 10.4 km rather than blowing apart on the first wall.

On the flatter and downhill sections created by the 395 m of undulation, resist the urge to soft-pedal, then over-cook the next ramp. Keep power steady through the dips and let speed take care of itself. If you do not know your ceiling, run the FTP estimator beforehand so your pacing target is grounded in real numbers.

Gearing

Gearing here is governed by the steepest pitches, not the average. For an HC climb averaging 9.69%, come prepared with a compact or sub-compact chainset paired to a wide-range cassette. A 34×32 is a sensible minimum, and 34×34 gives you more margin on the sharpest ramps and after the re-climbs out of each dip.

Check your setup before the ride. Confirm your smallest chainring, your largest sprocket, and that your rear derailleur can handle the cassette. Running out of gears on a wall this steep leaves you no options.

Summary

• Length: 10.4 km
• Average gradient: 9.69%
• Net elevation gain: 1,005 m
• Total ascent: 1,400 m
• Category: HC

Col de Mantet is a genuine HC test: long, steep, and undulating enough that the effort outstrips its net numbers. Pace to your power, gear low, and respect the ramps.